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Process‐based Modeling of Ammonia Emission from Beef Cattle Feedyards with the Integrated Farm Systems Model
Author(s) -
Waldrip Heidi M.,
Rotz C. Alan,
Hafner Sasha D.,
Todd Richard W.,
Cole N. Andy
Publication year - 2014
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2013.09.0354
Subject(s) - environmental science , manure , volatilisation , livestock , particulates , manure management , ammonia , beef cattle , atmospheric sciences , environmental engineering , chemistry , zoology , ecology , organic chemistry , biology , geology
Ammonia (NH 3 ) volatilization from manure in beef cattle feedyards results in loss of agronomically important nitrogen (N) and potentially leads to overfertilization and acidification of aquatic and terrestrial ecosystems. In addition, NH 3 is involved in the formation of atmospheric fine particulate matter (PM 2.5 ), which can affect human health. Process‐based models have been developed to estimate NH 3 emissions from various livestock production systems; however, little work has been conducted to assess their accuracy for large, open‐lot beef cattle feedyards. This work describes the extension of an existing process‐based model, the Integrated Farm Systems Model (IFSM), to include simulation of N dynamics in this type of system. To evaluate the model, IFSM‐simulated daily per capita NH 3 emission rates were compared with emissions data collected from two commercial feedyards in the Texas High Plains from 2007 to 2009. Model predictions were in good agreement with observations and were sensitive to variations in air temperature and dietary crude protein concentration. Predicted mean daily NH 3 emission rates for the two feedyards had 71 to 81% agreement with observations. In addition, IFSM estimates of annual feedyard emissions were within 11 to 24% of observations, whereas a constant emission factor currently in use by the USEPA underestimated feedyard emissions by as much as 79%. The results from this study indicate that IFSM can quantify average feedyard NH 3 emissions, assist with emissions reporting, provide accurate information for legislators and policymakers, investigate methods to mitigate NH 3 losses, and evaluate the effects of specific management practices on farm nutrient balances.